s={1,2,3,4,5,6,7,8,9}
s.add(11)#添加
print(s)
s.remove(5)#删除
print(s)
s.clear()#清空
print(s)

# 遍历
s1={1,2,3,4,5,6,7,8,9}
for i in s1:
    print(i)

for index,i in enumerate(s1):
    print(index,i)

for index,i in enumerate(s1,start=10):
    print(index,i)